Use of stimulus on Microchip MPLAB SIM query

Question

Hi - does anyone know if is possible to use the stimulus tool on this simulator to inject an asynchronous 1Hz square wave signal into the Timer0 signal input pin on a 16F630 microcontroller? I have tried studying the help content on this tool but cannot make sense of it. It only gives a very sketchy description of the setting up of a test file. Considering that one can inject a series of controlled inputs into a register, I would have thought that my requirement was simple. Have I missed something obvious? Any comment would be appreciated.

Former Member · Accepted Answer

MPLAB SIM does offer clock stimulus option, and can be set a wide range of frequency and duty cycles as a function of cycles.

The "cycle" refers to instruction cycles. Since the 8 bit PIC micro has four Fosc system clocks for every instruction cycle, a 4 MHz Fosc will produce 1 MIPS operation.

Referring to PIC16F630 datasheet FIGURE 4-1: BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER, an external input is available on the T0CKI pin with T0CON<bit5>, T0CS, TMR0 Clock Source Select bit equal to 1. However, T0CON<PS2:PS0>, Prescaler Rate Select bits, equal to 000'b is 1:2, requiring the input twice the frequency as the desired interrupt rate. Therefore, the simulator clock input will two times the desired timer 0 overflow rate.

As a result, the simulators clock stimulus will be 2 Hz, on T0CKI/RA2 pin, with 250000 cycles on low and high cycle count perameter.

There in an asynchronous input option on the simulator, but the clock stimulus is synchronous by nature of a clock operation.

Hope all this helps ?